dmaengine: at_xdmac: get the number of DMA channels from device tree

In case of kernel runs in non-secure mode, the number of DMA channels can
be got from device tree since the value read from GTYPE register is "0" as
it's always secured.

As the number of channels can never be negative, update them to the type
"unsigned".

This is required for LAN969x.

Signed-off-by: Tony Han <tony.han@microchip.com>
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Link: https://patch.msgid.link/20251203121208.1269487-1-robert.marko@sartura.hr
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index ada96d490847ce022ccee5225e3c0592fa90482b..901971e8bae69643df0140425a5092bf69a915d5 100644 (file)
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -2247,12 +2247,29 @@ static int __maybe_unused atmel_xdmac_runtime_resume(struct device *dev)
        return clk_enable(atxdmac->clk);
 }
 
+static inline int at_xdmac_get_channel_number(struct platform_device *pdev,
+                                             u32 reg, u32 *pchannels)
+{
+       int     ret;
+
+       if (reg) {
+               *pchannels = AT_XDMAC_NB_CH(reg);
+               return 0;
+       }
+
+       ret = of_property_read_u32(pdev->dev.of_node, "dma-channels", pchannels);
+       if (ret)
+               dev_err(&pdev->dev, "can't get number of channels\n");
+
+       return ret;
+}
+
 static int at_xdmac_probe(struct platform_device *pdev)
 {
        struct at_xdmac *atxdmac;
-       int             irq, nr_channels, i, ret;
+       int             irq, ret;
        void __iomem    *base;
-       u32             reg;
+       u32             nr_channels, i, reg;
 
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
@@ -2268,7 +2285,10 @@ static int at_xdmac_probe(struct platform_device *pdev)
         * of channels to do the allocation.
         */
        reg = readl_relaxed(base + AT_XDMAC_GTYPE);
-       nr_channels = AT_XDMAC_NB_CH(reg);
+       ret = at_xdmac_get_channel_number(pdev, reg, &nr_channels);
+       if (ret)
+               return ret;
+
        if (nr_channels > AT_XDMAC_MAX_CHAN) {
                dev_err(&pdev->dev, "invalid number of channels (%u)\n",
                        nr_channels);